Timer-based warning structure for detecting and indicating an overloaded diesel particulate filter

ABSTRACT

An engine ( 12 ) has an exhaust system ( 16 ) containing a diesel particulate filter (DPF  20 ) and timer-based warning structure ( 30 ) for detecting and indicating particulate overloading of the DPF as the engine runs.

FIELD OF THE INVENTION

This invention relates to monitoring after-treatment devices in engineexhaust systems in motor vehicles, and in particular to a time-basedstructure for detecting and indicating an overloaded diesel particulatefilter (DPF).

BACKGROUND OF THE INVENTION

A DPF treats engine exhaust passing through the engine exhaust system bytrapping particulate matter to prevent its escape to atmosphere. Fromtime to time, a DPF requires regeneration in order to keep the trappedmatter from imposing excessive back-pressure on the engine. Regenerationinvolves creating conditions that will burn off trapped particulateswhose unchecked accumulation would otherwise eventually create excessiveback-pressure. Such conditions may be created naturally as the engineoperates, with the resulting regeneration being sometimes referred to asnatural regeneration. Such conditions may also be created by adeliberate request for regeneration. The resulting regeneration issometimes referred to active regeneration.

A vehicle that is powered by an internal combustion engine whose exhaustsystem contains a DPF may operate over an extended period of time duringwhich no regeneration of the DPF occurs. As trapped particulatesaccumulate, they impose increasing back-pressure on the engine.

It is known to use an engine control system to automatically initiate aregeneration request when the amount of trapped particulates reaches alevel appropriate for regeneration. It is also known to provide awarning to a driver of the vehicle when the amount of trappedparticulates reaches a level at which active regeneration is appropriateso that the driver can manually initiate an active regeneration, forexample by operating a switch that issues a regeneration request to theengine control system.

SUMMARY OF THE INVENTION

One aspect of the invention relates to an engine comprising an exhaustsystem containing a diesel particulate filter (DPF) and timer-basedwarning structure for detecting and indicating particulate overloadingof the DPF as the engine runs.

The warning structure comprises a) a source for providing datarepresenting current particulate loading of the DPF, b) processingapparatus for i) repeatedly processing the current particulate loadingdata and data defining a threshold level of particulate loading at whicha request for regeneration of the DPF should be issued, and ii) when aresult of that processing discloses that the current particulate loadingis at least as great as the threshold level, enabling an indicator, andiii) when processing of the current particulate loading data and datadefining a hierarchy of zones of successively greater particulateoverloading of the DPF greater than the threshold level discloses thatthe current particulate loading has remained in one of those zones for alength of time set by a timer, causing the enabled indicator to give anindication that the DPF has become overloaded.

Another aspect relates to an engine comprising an exhaust systemcontaining a diesel particulate filter (DPF), and timer-based warningstructure for detecting and indicating particulate overloading of theDPF as the engine runs.

The warning structure comprises a) a source for providing datarepresenting current particulate loading of the DPF, b) processingapparatus for repeatedly processing the current particulate loading dataand data defining a hierarchy of zones of successively greaterparticulate overloading of the DPF, wherein each zone comprises a rangebounded by a respective lower level of particulate loading and arespective upper level of particulate loading, and c) the processingapparatus comprises, for each zone, an input stage for determining ifthe current particulate loading is greater than some level of loading, atimer that runs concurrently with the input stage disclosing thatcurrent particulate loading is greater than that level, and an outputstage that issues a signal to indicate when the respective timer hasdisclosed that particulate loading has remained greater than that levelfor some set length of time.

The foregoing, along with further features and advantages of theinvention, will be seen in the following disclosure of a presentlypreferred embodiment of the invention depicting the best modecontemplated at this time for carrying out the invention. Thisspecification includes drawings, now briefly described as follows.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows portions of an engine and exhaust system relevant to thepresent invention in a motor vehicle.

FIG. 2 is chart showing various conditions related to the state of a DPFin the exhaust system.

FIGS. 3A and 3B collectively comprise a schematic illustration of apresently preferred embodiment of timer-based warning structure inaccordance with principles of the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 shows a truck 10 that is propelled by a diesel engine 12. Engine12 has one or more processors 14 that processes data from varioussources to develop various data that is used for informational and/orcontrol purposes. The data processed by control system 14 may originateat external sources, such as sensors, and/or be generated internally.

Engine 12 also has an exhaust system 16 through which exhaust created bycombustion of a combustible mixture in combustion chambers of the engineis conveyed to a tail pipe 18 that opens to the surrounding atmosphere.Exhaust system 16 comprises one or more after-treatment devices, one ofwhich is a diesel particulate filter (DPF) 20 that traps exhaustparticulates (soot) so that they do not pass through to tail pipe 18.

As explained earlier, DPF 20 must be regenerated from time to time inorder to burn off trapped particulates. When a need for regeneration isdetermined by a frequently executed algorithm in a processor 14disclosing that the particulate load in DPF 20 has reached a point whereregeneration is required, a regeneration request is issued. Ifconditions are suitable for initiating regeneration, the engine controlsystem may then automatically initiate regeneration, such as by changingfueling and/or air management, to suitably condition the exhaust. Ifconditions for regeneration are not suitable, regeneration is delayed,and particulates continue to accumulate in DPF 20 as engine 12 continuesrunning. Some initial overloading of the DPF is tolerable, but beyondthat, the operator of truck 10 needs to be alerted.

The chart of FIG. 2 defines seven possible states for DPF 20: DPFmissing; DPF leaking; DPF clean; DPF partly-loaded with soot; DPF loadedwith soot to normal regeneration trigger point; DPF overloaded with sootgreater than normal regeneration trigger point; and DPF severelyoverloaded.

As shown by FIG. 2, each state has been defined in a processor 14 by arespective data value for a parameter STATE_EGBP_PF, using the numbers“7” through “1” inclusive in descending order.

Certain recommendations by the industry suggest that four levels of sootoverloading (Service, Warning, Stop, Critical) be identified and madeknown in some way to the operator of a motor vehicle that has a DPF inits exhaust system. While the existing data values shown in FIG. 2define important reference points for the amount of soot loading in DPF20, they do not provide direct correspondence with the industryrecommendations.

The present invention adapts the data values of FIG. 2 for use inconforming to industry recommendations.

A processor 14 processes data according to a time-based warningstructure 30 shown in FIGS. 3A and 3B. The processed data comprises thecurrent data value for parameter STATE_EGBP_PF and a selectable datavalue for each of eight parameters C_STATE_EGBP_PF1, C_STATE_EGBP_PF2,C_STATE_EGBP_PF3, C_STATE_EGBP_PF4, C_STATE_EGBP_PF5, C_STATE_EGBP_PF6,C_STATE_EGBP_PF7, C_STATE_EGBP_PF8.

While the data values for the each of the latter eight parameters can beselected from any of the values “7” through “1” in FIG. 2, the use ofonly “2” and “1” is needed to conform warning structure 30 to industryrecommendations.

Warning structure 30 comprises four sections 32, 34, 36, and 38 thatfunction to detect and indicate a respective one of these four portionsof the range of DPF soot loading greater than normal regenerationtrigger point.

Section 32 is designated “Request Service” to correspond to “Service” ofthe industry recommendations; section 34, “Warn Level” to correspond to“Warning” of the industry recommendations; section 36, “Stop Level” tocorrespond to “Stop” of the industry recommendations; and section 38,“Severe Level” to correspond to “Critical” of the industryrecommendations.

Each section 32, 34, 36, and 38 comprises a similar processing strategythat uses three comparison functions, an AND logic function, and a timerfunction. Two of the comparison functions and the AND logic functionform an input stage, and the third comparison function forms an outputstage to which the timer function is one input. The other input to thethird comparison function is a parameter that sets the length of timethat the timer must run in order for the output stage to issue a signalthat the time has elapsed.

Section 32 comprises a comparison function 40 that compares the currentvalue for STATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_1_1and a comparison function 42 that compares the current value forSTATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_2. When theamount of particulates in DPF 20 are within a range defined byC_STATE_EGBP_PF_1 and C_STATE_EGBP_PF_2, an AND logic function 44enables a timer function 46 to run.

The running time on function 46 (parameter DPF REQ_TMR) is compared witha reference time (parameter DPF REQ_TM) by a comparison function 48.When the running time exceeds the reference time, a signal representedby parameter REQ_DPF is given.

Section 34 comprises a comparison function 50 that compares the currentvalue for STATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_3and a comparison function 52 that compares the current value forSTATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_4. When theamount of particulates in DPF 20 are within a range defined byC_STATE_EGBP_PF_3 and C_STATE_EGBP_PF_4, an AND logic function 54enables a timer function 56 to run.

The running time on function 56 (parameter DPF_WARNLVL_TMR) is comparedwith a reference time (parameter DPF_WARNLVL_TM) by a comparisonfunction 58. When the running time exceeds the reference time, a signalrepresented by parameter WARN_DPF is given.

Section 36 comprises a comparison function 60 that compares the currentvalue for STATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_5and a comparison function 62 that compares the current value forSTATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_6. When theamount of particulates in DPF 20 are within a range defined byC_STATE_EGBP_PF_5 and C_STATE_EGBP_PF_6, an AND logic function 64enables a timer function 66 to run.

The running time on function 66 (parameter DPF_STOPLVL_TMR) is comparedwith a reference time (parameter DPF_STOPLVL_TM) by a comparisonfunction 68. When the running time exceeds the reference time, a signalrepresented by parameter STOP_DPF_DERATE_LVL_1 is given.

Section 38 comprises a comparison function 70 that compares the currentvalue for STATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_7and a comparison function 72 that compares the current value forSTATE_EGBP_PF and the value of a parameter C_STATE_EGBP_PF_8. When theamount of particulates in DPF 20 are within a range defined byC_STATE_EGBP_PF_7 and C_STATE_EGBP_PF_8, an AND logic function 74enables a timer function 76 to run.

The running time on function 76 (parameter DPF_SEVLVL_TMR) is comparedwith a reference time (parameter DPF_SEVLVL_TM) by a comparison function78. When the running time exceeds the reference time, a signalrepresented by parameter SEVERE_DPF_DERATE_LVL_2 is given.

Parameter REQ_DPF is an input to a switch function 80 that is used tooperate an indicator shown as a lamp 82. The state of switch function80, either ON or OFF, is controlled by a parameter DPF_LAMP_FLSH that isprovided by the output of an OR logic function 84 to which parametersWARN_DPF, STOP_DPF_DERATE_LVL_1, and SEVERE_DPF_DERATE_LVL_2 are inputs.The latter two parameters are also inputs to an OR logic function 86.

The four sections 32, 34, 36, and 38 enable the conditions that startthe respective timers and the length of time that each timer will runbefore giving a signal at a respective output to be set as deemedappropriate for a particular vehicle and/or engine.

By selecting from “DPF overloaded with soot greater than normalregeneration trigger point” (“2”) and “DPF severely overloaded” (1), inconjunction with SELECTING values for DPF_REQ_TM, DPF_WARNLVL_TM,DPF_STOPLVL_TM, and DPF_SEVLVL_TM, it is possible to conform to theindustry recommendations for alerting the operator.

In one example, a selection of STATE_EGBP_PF=2 for bothC_STATE_EGBP_PF_1 and C_STATE_EGBP_PF_2, and a value of ten minutes forDPF_REQ_TM will cause REQ_DPF to enable switch function 80 ten minutesafter a regeneration request has been issued and the engine continuesrunning without any active regeneration having commenced.

A selection of STATE_EGBP_PF=2 for both C_STATE_EGBP_PF_3 andC_STATE_EGBP_PF_4, and a value of sixty minutes for DPF_WARNLVL_TM willcause WARN_DPF to operate switch function 80 to ON state after sixtyminutes of continued running of the engine without any activeregeneration having commenced after the regeneration request. Withswitch function 80 both enabled and operated, lamp 82 lights to give awarning to the vehicle operator.

A selection of STATE_EGBP_PF=1 for both C_STATE_EGBP_PF_5 andC_STATE_EGBP_PF_6, and a value of five minutes for DPF_STOPLVL_TM willcause the state of STOP_DPF_DERATE_LVL_1 to change. If timer function 46is kept from being reset, STOP_DPF_DERATE_LVL_1 will continue to keepswitch function 80 in the ON state via OR logic function 84 five minutesafter the change in STATE_EGBP_PF from “2” to “1”. It also causes theengine control system to de-rate engine 12. To indicate the continuedlack of regeneration, STOP_DPF_DERATE_LVL_1 will also illuminate asecond lamp 88 via OR logic function 86.

A selection of STATE_EGBP_PF=1 for both C_STATE_EGBP_PF_7 andC_STATE_EGBP_PF_8, and a value of thirty minutes for DPF_SEVLVL_TM willcause SEVERE_DPF_DERATE_LVL_2 to continue to keep switch function 80 ONvia OR logic function 84 thirty minutes after the change inSTATE_EGBP_PF from “2” to “1”. It will also de-rate the engine even moreseverely than did STOP_DPF_DERATE_LVL_1 and will continue to illuminatelamp 88.

While a presently preferred embodiment of the invention has beenillustrated and described, it should be appreciated that principles ofthe invention apply to all embodiments falling within the scope of theinvention that is defined as follows.

1. An engine comprising: an exhaust system containing a dieselparticulate filter (DPF); and timer-based warning structure fordetecting and indicating particulate overloading of the DPF as theengine runs, the warning structure comprising, a) a source for providingdata representing current particulate loading of the DPF, b) processingapparatus for i) repeatedly processing the current particulate loadingdata and data defining a threshold level of particulate loading at whicha request for regeneration of the DPF should be issued, and ii) when aresult of that processing discloses that the current particulate loadingis at least as great as the threshold level, enabling an indicator, andiii) when processing of the current particulate loading data and datadefining a hierarchy of zones of successively greater particulateoverloading of the DPF greater than the threshold level discloses thatthe current particulate loading has remained in one of those zones for alength of time set by a timer, causing the enabled indicator to give anindication that the DPF has become overloaded.
 2. An engine as set forthin claim 1 wherein the data defining a hierarchy of zones defines first,second, and third zones of successively greater particulate overloadingin that order, and the first zone has a lower limit equal to thethreshold level.
 3. An engine as set forth in claim 2 wherein whenprocessing of the current particulate loading data and data defining thehierarchy of zones discloses that current particulate loading hasremained in the second zone for a length of time set by a timer, theprocessing apparatus issues an engine de-rate request to an enginecontrol strategy for de-rating the engine.
 4. An engine as set forth inclaim 3 wherein when processing of the current particulate loading dataand data defining the hierarchy of zones discloses that currentparticulate loading has remained in the third zone for a length of timeset by a timer, the processing apparatus issues an engine de-raterequest that is more extreme than the de-rate request issued inconsequence of particulate loading remaining in the second zone.
 5. Anengine comprising: an exhaust system containing a diesel particulatefilter (DPF); and timer-based warning structure for detecting andindicating particulate overloading of the DPF as the engine runs, thewarning structure comprising, a) a source for providing datarepresenting current particulate loading of the DPF, b) processingapparatus for repeatedly processing the current particulate loading dataand data defining a hierarchy of zones of successively greaterparticulate overloading of the DPF, wherein each zone comprises a rangebounded by a respective lower level of particulate loading and arespective upper level of particulate loading, and c) the processingapparatus comprises, for each zone, an input stage for determining ifthe current particulate loading is greater than some level of loading, atimer that runs concurrently with the input stage disclosing thatcurrent particulate loading is greater than that level, and an outputstage that issues a signal to indicate when the respective timer hasdisclosed that particulate loading has remained greater than that levelfor some set length of time.
 6. An engine as set forth in claim 5wherein each input stage comprises two comparison functions and an ANDlogic function that processes outputs of the AND logic function.
 7. Anengine as set forth in claim 5 wherein each output stage comprises acomparison function to which the timer is one input and to which aparameter for setting the respective length of time that the respectivetimer must run in order for the output stage to issue the respectivesignal is another input.
 8. An engine as set forth in claim 5 furtherincluding one or more indicators that are operated by signals from oneor more output stages.
 9. An engine as set forth in claim 8 wherein theone or more indicators comprise lamps that disposed for viewing by anoperator of a motor vehicle containing the engine.
 10. An engine as setforth in claim 5 further including an engine control system, and whereinrespective signals from certain output stages cause the control systemto de-rate the engine to respective de-rate levels.